More than 700,000 men, women, and children working in livestock production are at risk for occupational lung disease related to organic dust exposures. The primary goals of this project are to evaluate new methods for measuring inhalable particulates, endotoxins, and glucans/ergosterols that can be used to help establish occupational exposure guidelines for complex organic dusts in swine, poultry, and dairy environments, and to evaluate and develop correction factors for direct-reading aerosol instruments that can be readily used by practitioners for interventions. The performance of inhalable samplers including the IOM, IOM with Multifoam discs, and Button Sampler will be compared to traditional gravimetric methods for total and respirable dusts under controlled laboratory conditions and in the field. The utility and performance of these devices for measuring endotoxins and glucans/ergosterols will also be determined. Analysis using both assay (LAL and monoclonal antibody) and chemical (mass spectrometry) methods will help elucidate relationships between specific chemical components and potency of these bacterial and fungal products in the various organic dust matrices. In the same laboratory and field experiments two direct-reading devices, the DataRAM and HAM, will be compared to the gravimetric methods, and their performance characterized in response to particle size distributions determined using a Grimm. Their suitability for practical applications in these environments will also be determined. This project addresses the need for more research related to organic dusts in agriculture identified by the NIOSH Board of Scientific Counselors, as well as developing practical cost-effective tools for application in engineering and other interventions, also identified as a priority. This study will address several priority areas of the National Occupational Research Agenda (NORA): Asthma and Chronic Obstructive Pulmonary Disease, Mixed Exposures, and Exposure Assessment Methods. This project also addresses the NIOSH Agricultural Centers priority area to develop and conduct research related to the prevention of occupational disease of agricultural workers and their families, with an emphasis on multi-disciplinary research and the development and evaluation of control technologies.